Shearing machine and method



Sept. 20, 1966 A. F. HAUSMAN ET AL 3,273,434

SHEARING MACHINE AND METHOD 7 Sheets-Sheet- 1 Filed Nov. 24, 1964INVENTORS. r 6' Hnus/vmv 31 1769 Fkux/Z C HIP/J5 HTTOKNEyS.

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SHEARING MACHINE AND METHOD 7 Sheets-Sheet 2 Filed NOV. 24, 1964 II.in:- n u E MWn/IQQ Sept. 20, 1966 HAUSMAN ET AL 3,273,434

SHEARING MACHINE AND METHOD Filed Nov. 24, 1964 '7 Sheets-Sheet 5 y M54/! I7 CHIP/-15. M, F

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Sept. 20, 1966 HAUSMAN ETAL 3,273,434

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Sept. 20, 1966 HAUSMAN ETAL 3,273,434

SHEARING MACHINE AND METHOD Filed Nov. 24, 1964 7 Sheets-Sheet 5 f I. E7 INVENTORS.

' mam? F. Mama/v /mw ffl/X K m/ w' Sfipfi. 20, 1966 F HAU$MA|\| ET ALSHEARING MACHINE AND METHOD 7 Sheets-Sheet 6 Filed Nov. 24, 1964 7Sheets-Sheet 7 Sept. 20, 1966 A. F. HAUSMAN ETAL SHEARING MACHINE ANDMETHOD Filed Nov. 24, 1964 United States Patent 3,273,434 SHEARINGMACHINE AND METHOD Albert F. Hausman and Felix A. Chiplis, Indianapolis,Ind., assiguors to Amsted Industries, Incorporated, Chicago, III., acorporation of New Jersey Filed Nov. 24, 1964, Ser. No. 413,539 29Claims. (Cl. 8355) This is a continuation-in-part of application SerialNo. 144,756, filed October 12, 1961, now abandoned, for a Punch Press.

This invention relates to the die shearing of material such as metal, inwhich the material is stressed in shear to the point of fracture, thatis, beyond its ultimate strength, between two cutting edges of diecomponents, which are forced toward each other in passing relation, thatis, in the direction of, and on opposite sides of, the plane of shearstress. The invention relates especially to shearing operations in whichthe character and trueness of the cut face or faces are criticallysignificant.

Operations which use die shearing include, for example, the punching ofstrip or sheet stock in punch presses to provide holes through thestock, the cutting of blanks from stock in blanking presses, the cuttingof pieces from continuous rod or wire, etc.

The most common form of press used for performing operations of the kindmentioned is of the crank type in which a reciprocable member carryingone of the die components, such as the punch of a punch and die set, isconnected through a connecting rod to a crank or eccen tric on a driveshaft. The motion of the movable die or punch is essentially a harmonicmotion in which the velocity of the die or punch is relatively low anddecreasing as it approaches the work and moves through its cuttingoperation. In any given machine, the linear velocity of the movable dieas it engages the work and performs its cutting operation will dependupon the speed of the drive shaft; and where the work is automaticallyfed by mechanism driven from the same drive shaft, the linear speed ofthe movable die will depend upon the feeding frequency. In suchconventional machines, the lineal speeds of the moving punch or othershear die as it approaches and progresses through its shearing operationmay be of the order of 1 foot per second and the practical upper limitdoes not exceed about 2 feet per second.

Another conventional shearing machine, commonly used for cut-offoperations, employs a cam to drive the cut-off die. In such machines,the die velocity accelerates from substantially zero at the start of thecutting movement to a maximum near the end of the die cutting movement.In this type of machine also, the practical limit on die velocity,imposed by limitations of operable cam shapes, is of the order of 2 feetper second as a maximum.

As is known, shearing dies used in conventional machines require certaincritical clearances, depending on the type of material being cut, itsthickness, and its hardness; and with those critical operatingclearances, the dies produce certain characteristics results at the cutedges. As the shearing action of the dies begins, the stock undergoesplastic deformation which produces a rounded edge, or edge radius,bordering the contact area of each die on the face of the material. Asdie movement continues, the die edges penetrate and cut the material,which produces a substantially straight out band on the cut face. Thepenetration reduces the cross-section of stock remaining between thedies, and as penetration increases, fracture occurs through theremaining stock cross-section, and this produces a cleavage surfacewhich is usually irregular and rough and which lies at an angle to thedirection of die movement. The edge radius, the cut band, and the angledcleavage surface appear on both edge faces produced by the shearing. Ina punched hole, the plastic See deformation produces .a substantial edgeradius at the punch-entrance end of the hole, the penetration produces anarrow substantially cylindrical cut band, and the fracture produces afrusto-conical cleavage surface which flares outward from the cut bandto the opposite face of the stock. If a substantially cylindrical holeis desired, it is necessary with conventional operations first to puncha hole having these non-cylindrical wall portions, and then to shave thehole to the desired cylindrical configuration and size in a separatesecondary operation. Similar secondary operations are necessary on otherconventionally sheared parts if it is desired to produce true faces atright angles to the work-piece surface.

In accordance with the present invention, it has been found that greatlyimproved results can be obtained, especially in certain types of work,by performing the cutting operation at linear speeds well above thosepracticably attainable in conventional machines. With such high speeds,clearances can be reduced well below the critical ranges required withconventional operation of corresponding dies on corresponding stock.With the higher speeds and narrower clearances, greatly improved andtruer edge faces are produced by the shearing, to a degree which oftenpermits secondary shearing operations and other truing operations to beeliminated. In hole piercing operations, for example, at linear punchingspeeds in accordance with the present invention, the tendency of thecleavage surface to flare is greatly reduced and is less dependent onthe nature of the metal being pierced. In fact, without producing punchand die wear at a rate which would render the operation impractical, itis possible with high punching speeds, by appropriate selection ofrelative punch and die-hole diameters, to produce pierced holes havingan essentially uniform diameter through the entire thickness of themetal, or even holes which are smaller on the die side of the metal thanon the punch side. Moreover, the trueness and smoothness of the surfacesof the holes is comparable to or better than that produced by theconventional combination of piercing and shaving operations. Theimprovements tend to reduce or eliminate ditficulties arising from thenature of the metal, which gives the manufacturer greater freedom ofchoice of materials and permits use of less expensive or otherwise moredesirable grades or types of material which would not be practical touse with conventional cutting operations.

In the case of blanking and simple shearing, the high die shearingspeeds promote smoothness and increase trueness of the edge faces of theblanks. In cut-off operations, such as in shearing pieces from rod orother continuous lengths of stock, the high speed shearing operationswill produce substantially undistorted square and flat ends where priorshearing produced distorted ends and rough and angular end faces.

In carrying out our invention we drive the movable cutting tool, or aset of cutting tools, through the working stroke by a relatively massiveram accelerated to a velocity of at least several hundred feet perminute. Conveniently, the tools are separate from the ram and are drivenby impact of the ram after it has been accelerated to the high velocity.While it is tool velocity which acts on the work, it is convenient tomeasure and refer to ram velocity. Tool velocity is at least equivalentto ram velocity. The lineal velocity to which the ram should beaccelerated in any particular case will vary with the character andsection of the stock material. The mass and velocity of the ram must ofcourse provide sufficient energy to shear and fracture the materialbeing Worked on, and excess energy should be held within reasonablelimits since it must be absorbed by the machine without performinguseful work. In general, the minimum lineal tool velocities which arepractical in accordance with the invention are velocities of at least 6to 8 feet per second, with the lower velocities generally applicable topunching operations and with higher minimum velocities desirable forcut-off operations. Desirably, velocities higher than the minimums areused, and We preferably use velocities of at least to 12 feet persecond. The velocities used may be substantially higher than theseminimums, with improved results, and we have used velocities of theorder of 50 feet per second in cut-off operations. While the shearingoperation itself appears to impose no top limit on the velocity used,practical considerations require that the velocity not exceed thelimitations of the mechanical design and strength of the die componentsand the machine structure.

Preferably, the ram is accelerated by subjecting it to force derivedfrom a confined body of air or other gas maintained under elevatedpressure. In a cyclically operating machine, the ram is retracted withaccompanying compression of the gas by power-operated means and, afterretraction, is abruptly released to permit it to accelerate and acquiresufficient momentum to force the cutting tool through the work at highvelocity. Desirably, the change in volume of the confined gas whichaccompanies retraction and advance of the ram is small relative to thetotal volume of the gas, in order that the ramaccelerating force exertedby the gas will not decrease unduly as the ram advances.

In a preferred form of machine embodying the invention, a portion of theconfined gas is contained in a cylinder within which a piston isdisposed. Either the piston or the cylinder is stationary, while theother of those elements is operatively connected to the ram. Where thepiston is the stationary element, the ram and cylinder may convenientlybe integral with each other. Means for retracting and releasingthe rammay take various forms such, for example, as a rotating, spiral camhaving a ram retracting lobe which terminates abruptly. Another suitableform of such a means comprises a crank-reciprocated ram-retractor and alatch which retains the ram in retracted position while the retractoradvances toward the work and is then abruptly released. The workingstroke of the ram is limited by a stop positioned to be engaged by theram after it has struck the cutting tool and forced it through thecutting stroke, and to pervent substantial over-travel. Retraction ofthe cutting tool after performance of its cutting stroke may in someinstances be effected by a spring; while in other instances it may bedesirable to effect its retraction by power-operated means operating intimed relation with the ram-retracting means. Perferably, the work-pieceis held against the stationary die component during the shearingoperation, as by a stripper plate or other hold-down device, under highpressure.

Other objects and features of the invention will appear from thefollowing more detailed description and from the accompanying drawings,in which:

FIG. 1 is a side elevation of a punch press embodying the invention andadapted to punch holes in successively fed, discrete blanks;

FIG. 2 is a rear elevation of the punch press of FIG 1;

FIG. 3 is a vertical section through the bottom portion of the press onthe line 33 of FIG. 1;

FIG. 4 is a horizontal section on the line 4-4 of FIG 3;

FIG. 5 is a detail view in partial section on the line 5-5 of FIG. 1;

FIG. 6 is a fragmental vertical section on the line 6-6 of FIG. 2;

FIG. 7 is a fragmental plan view of another machine which embodies theinvention and is adapted to cut pieces of predetermined length from acontinuous rod or wire;

FIG. 8 is a vertical, axial section through the shearing mechanism ofthe machine illustrated in FIG. 7, taken on the line 8-8 of FIG. 7,showing the ram and cutting tool in their retracted positions;

FIG. 9 is a vertical section onthe line 99 of FIG. 8;

FIG. 10 is a horizontal section on the line 10-10 of FIG. 8; and

FIG. 11 is a view similar to FIG. 8 showing the positions of the ram andcutting tool at the termination of their working strokes.

The punch press illustrated in FIGS. 16 embodies a frame comprisingvertical, parallel side plates 10 and 11 secured at their lower ends toa base 12 and at their upper ends to a top plate 13. Between the sideplates, a hammer or ram 15 is mounted for vertical reciprocation.Conveniently, the ram 15 is a rectangular parallelapiped of metal thecenter portion of which is cut out to provide a vertically elongatedopening extending through the ram from front to back. Guide rollers 16supported in any convenient manner from the frame engage the sides, thefront, and the back of the ram to guide it in its verticalreciprocation.

Connected to the top of the ram 15 is a piston rod 17 which extendsupwardly through the top plate 13 and projects into the open lower endof a cylinder 18, where it is provided with a piston 19. Desirably, theupper end of the cylinder 18 is enlarged to provide an accumulator 2%adapted to contain a considerable volume of air or other gas underpressure. The supply of air or other gas under pressure in the cylinderand accumulator is maintained through a pipe 21 containing a suitablepressure-regulating valve 22.

For the purpose of raising the ram 15 against the fluid pressure in thecylinder 18, we provide a main shaft 25 which is rotatably supported insuitable bearings 26 from the side plates 10 and 11 and which extendsthrough vertical slots in the sides of the ram 15, such slots being longenough to permit the desired vertical movement of the ram. Between thesides of the ram, there is secured to the shaft 25 a spiral cam 27 whichengages a cam- =following roller 28 mounted in the ram. The cam 27 isshaped so that as the shaft 25 rotates, in a counterclockwise directionas shown in FIG. 1, the cam will gradually raise the ram 15 and piston19 against the pressure in the cylinder and accumulator and thenabruptly move out of engagement with the roller 28 to permit the ram todescend rapidly under the fluid pressure exerted on the piston 19.Desirably, descent of the ram is limited by ram-stops 29 supported onthe base 12 in position to be engaged by the descending ram before theroller 28 can impinge on the low point of the cam 27. The shaft 25projects outwardly beyond the bearing 26 on the side plate It] and isprovided with a pulley 30 driven through a belt 31 from any convenientsource of power.

The arrangement of punch and die mechanism embodied in the machine willof course depend upon the nature of the work the press is to perform.The punch press shown in FIGS. 1-6 is designed for perforating small,automatically fed blanks, specifically, for providing the pitch holes inthe link plates P of a powertransmission chain. In the arrangementshown, the base 12 is recessed for the reception of a die pad 32containing die bushings 33. A hold-down and stripper plate 34 carried byguide rods is normally urged downward to hold the link plates P againstthe face of the die pad 32 and bushings 33, by springs 152 acting on acrosshead 153 carried by the lower ends of the guide rods. The pressureon the plates P is desirably about 1200 lbs. per square inch. A cam 154driven in timed relation with the feed mechanism, described below, liftsthe plate 34 slightly during feed movement of the link plates. The plate34 slidably receives and guides punches 35 respectively aligned with theholes in the die bushings. Well above the stripper 34 the punches 35 areprovided with enlarged heads 36 having at their lower ends still largerflanges 37. Upward movement of the punches in the stripper 34 is limitedby a stop plate 38 supported from the ram stops 29 and provided withopenings large enough to pass the heads 36 but too small to pass thehead-flanges 37. Desirably, the bottom .of the ram 15 is provided with apunch-engaging member 40 which is vertically adjustable in the ram tovary the extent to which the punches 35 are forced downwardly when theram descends. As shown, the member 40 is a plug screwthreaded into thebottom of the ram.

To raise the punches 35 after each descent of the ram, the punches areloosely received (FIG. 6) below their flanges 37 in openings in the endsof lifting arms 42 secured to a rock-shaft 43 rotatably supported fromthe side plates and 11. The shaft 43 projects outwardly beyond the sideplate 11 where (FIG. 1) there is secured to it an arm 44 projectingupwardly and carrying at its upper end a follower 45 engaged by a cam 46secured to the main shaft 25. A spring 47 acting on the arm 44 may beemployed to maintain the cam follower 45 in engagement with the cam 46.The cam 46 is so shaped and so oriented on the shaft 25 that promptlyafter the cam 27 has moved out of engagement with the cam follower 28and the ram has descended the cam 46 will rock the shaft 43 in adirection to cause the arms 42 of the cam 27. For this purpose themachine shown in FIGS. 1-6 embodies two independently operable latches,mounted respectively on the side plates 10 and 11. The latch on the sideplate 10 comprises (FIG. 3) a cup-like guide 50 mounted in a hole in theside plate '10 and adapted to receive a latch member 51 slidable in theguide between positions in which it lies respectively within andlaterally beyond the path of the descending ram 15. The latch 51 has ashank which projects outwardly beyond the guide 50 for operativeconnection to a lever 52 fulcrumed to the side plate 10 near the rearedge thereof.

The other latch mechanism, that carried by the side plate 11, isassociated with feeding mechanism to be described below. Such otherlatch mechanism comprising a cup like guide 55 mounted in a hole in theside plate 11 and arranged to receive a slidable latch member 56 which,like the latch member 51, can be projected into the path of the ram 15.As will be clear from FIGS. 3 and 4, the latch member 56 is providedinside the guide 55 with a notch receiving the intermediate portion ofan operating lever 57, which extends through slots in the front and backof the guide 55, and is fulcrumed at its rear end to the side plate 11.

As previously indicated, the machine shown in FIGS.

1-6 is intended for use in piercing the link plates of powertransmission chain. A supply of such plates to be pierced is containedin tubular magazine 60 supported vertically at the front of the machinewith its lower end received in a socket 61 which has an openingpermitting the plates in the magazine, while still stacked in superposedrelation, to pass downwardly through the socket until the lowermostplate rests on the upper surface of the base 12, as will be clear fromFIG. 6. The rear of the socket 61 is provided with a notch leading to aguide groove through which the plates to be pierced may be advanced fromthe socket 61 into piercing position over the dies 32. For the purposeof so advancing the link plates successively, we provide feed mechanismembodying a feed slide 62 mounted for fore-and-aft reciprocation in thefront portion of the base 12. To the inner end of the slide 62 there issecured a feed tongue 63 which rests on the upper surface of the base 12and which has a thickness slightly less than the link plates to bepierced. In rearward movement of the slide 62 from the position shown inFIG. 6,

the tongue 63 engages the lowermost link plate in the stack contained inthe magazine 60 and socket 61 and advances such plate toward piercingposition. As each plate is advanced, it forces ahead of its platespreviously fed, as will be clear from FIG. 4. -At the piercing positionlocating jaws 64 slidably mounted in the stripper 34 and the ram stops29 engage the ends of the link plate and retain it in proper positionduring the pirecing operation. As shown, each of the locating jaws 64 isprovided at its inner end with a pair of spaced rollers 65 which receivebetween them the rounded end of the link plate. The jaws 64 arespring-pressed inwardly by spring 66 toward positions determined byadjustable stop screws 67. As each link plate approaches piercingposition its rounded ends engage the forward rollers 65 on the locatingjaws 64 and force them outwardly to permit the link plate to move overthe dies 33, whereupon the springs 66 force the jaws inwardly causingthe rollers to grip the link plate and hold it in proper position forpiercing.

For the purpose of reciprocating the feed slide 62 we employ a feed cam70 rigidly secured to the drive shaft 25. The cam 70 serves to oscillatea pivotally mounted arm 71 connected through a link 72 to an arm 73rigidly secured to a rock-shaft 74 that extends transversely of themachine below the feed slide 62. Such slide is provided with a slotwhich receives the end of a second arm 75 rigidly secured to the shaft74. A spring 71' acts on the arm 71 to maintain a cam following roller76 on the arm in contact with the cam 70.

The cam 78 is so shaped and so oriented with respect to the earns 27 and46 that it retains the feed slide 62 in retracted position against theforce of the spring 71' until after the ram 15 has begun its upwardmovement and the fingers 42 have raised the punches to clear the platejust pierced so that such plate will be free to move when the feed slidedoes advance. For a reason which will become apparent hereinafter, thecam 70 places the feed slide in retracted position preferably before thecam reaches the top of its stroke and in any event before the cam, indescending, reaches a position where it would obstruct inward movementof the latch member 56.

Conveniently, the arm '71 is associated with the latch member 56 in sucha way that when the latch member is advanced to retain the ram 15 inelevated position the feed mechanism will be rendered inoperative. Forthis purpose, the guide 55 for the slide 56 is formed at its outer endwith a boss 78 on which the arm 71 is pivoted for oscillatory movement.The latch member 56 has a shank 79 which projects through such boss androtatably supports at its outer end a cross piece 80 from which a pairof parallel pins 81 project inwardly parallel to and on opposite sidesof the shank 79 for slidable reception in holes in the arm 71. Inwardlyfrom the arm 71 there is mounted on the guide 55 a stationary plate 82having holes 83 with which the pins 81 come into alignment as the feedslide 62 reaches the outer limit of its reciprocation.

In the normal, or retracted, position of the latch 56 the pins 8-1 liewithin the arm 71 in the position shown in FIG. 5 and do not projectinto the holes 86 of the stationary plate 82. Accordingly the arm 71 isfree to oscillate on the boss 78, carrying with it the pins 81 and thecross-piece 80. If it is desired to interrupt both reciprocation of theram 15 and operation of the feeding mechanism, the lever 57 is urgedinwardly, or to the right of FIG. 4. Unless the ram is at or near thetop of its stroke, such inward urging of the lever 57 can do no morethan force the inner end of the latch member 56 against the side of theram; but if the effort on the lever 57 is maintained, the ram will clearthe inner end of the latch member 56 as it reaches the top of itsstroke, and the latch member can be moved into fully advanced positionwhere it will prevent descent of the ram. As the inner end of the latchmember 56 moves into the path of the ram 15, the pins 81 which werepositioned in alignment with the holes 83 in the stationary plate 82when the feed side 62 reached retracted position will enter such holesand thus retain the feed slide in retracted position as the land of thecam 70, in continuing rotation of the shaft 25, moves out of engagementwith the cam fol-lower 76.

If it is desired to interrupt reciprocation of the ram 15 while stillleaving the feeding mechanism in operation, the operator will advancethe latch member 51 instead of the latch member 56. This operation iseffected byapplying an inward effort to the operating lever to cause thelatch member 51 to move beneath the ram 15 as the latter reaches theupper end of its stroke. Desirably, the clearance beneath the latchmembers 51 and 56 and the lower face of the ram 15 when such ram is atthe top of its stroke is made as small as practicable in order that thedescending ram will not attain an unduly high velocity before itimpinges on one or the other or both of the latch members. If desired,the latch members may be provided with hardened nose pieces 85 toreceive the impact of the descending ram, and such nose pieces mayproject laterally from the latch members to be received in slots 86 inthe guides 50 and 55, thus preventing rotation of the latch members inthe guides.

The operation of the machine illustrated should be evident from theabove description, but it may be summarized as follows: With a stack oflink plates in the magazine 60, with the latch members 51 and 56retracted,

and with the drive shaft 25 rotating in a counter-clockwise direction(FIG. 1), the cam 27 will alternately raise the ram 15 and permit it todescend under the influence of gravity and the fluid pressure existingwithin the cylinder-accumulator 1820. As the ram 15 approaches the lowerlimit of its stroke, it first strikes the heads of the punches 35 toeffect the piercing operation and then engages the stops 29, which limitits further descent. Desirably, the stops 29 are so positioned that theram will engage them before the roller 28 on the ram can come intocontact with the cam 27. As the cam 27, in its continuing rotation,engages the roller 28 and begins to raise the ram, the cam 46 operatesto lift the fingers 42 and restore the punches to raised position.Promptly thereafter the feed slide 62, which was in retracted positionwhen the ram began its descent, advances to feed a link plate from themagazine and to cause'ejection of the plate just pierced. Immediatelyfollowing the advance of the feed slide 62, the cam 70 operates to moveit into retracted position before the ram begins its next descent. Atany time while the machine is in operation, the lever 57 can be operatedto advance the latch member 56 and retain the ram in elevated positionand simultaneously to lock the arm '71 in a position which will retainthe feed-slide 62 retracted. If it should be desired to interruptreciprocation of the ram while permitting the feeding mechanism toremain in operation the latch member 51 instead of the latch member 56can be advanced to retain the ram in elevated position.

It will be understood that the proportions of the machine will dependupon the effort required to effect the piercing operation. A machinewhich we have employed to punch pitch holes 0.273 inch in diameter insoft steel link-plates 0.080 inch in thickness has the followingspecifications:

Weight of ram, piston rod and piston lbs 18 Stroke of ram inches 1 /2Piston diameter do 3 Volume of cylinder-accumulator (approx) cu. in 200Pressure in cylinder-accumulator p.s.i 50 Stroke frequency per min 300In such a machine, and with the air pressure specified, the ram willattain a velocity of 700 to 800 feet per minutel1 to 13 feet persecondbefore striking the punches and driving them downwardly to performthe punching operation. Since the piston displacement is only about ofthe total volume of the cylinder-accumulator, the pressure acting on thepiston 19 will not change significantly as the piston moves and willtherefore continue to exert its ram-accelerating effect throughout theentire down-stroke of the ram. The ram-accelerating pressure isindependent of the stroke frequency, which can be as high or higher thanwith conventional presses, and can be varied to suit the stock feed ratewithout affecting the shearing conditions.

Shearing velocity can be changed by varying the ram weight or stroke or,in a particular set-up, by adjusting the air pressure. A series ofexperimental operations were run on the machine described above, usingdifferent ram velocities and different die clearances, with thefollowing results.

In general, the holes produced in the link plates had smoother walls andless taper than those produced by conventional punching equipment, andit was readily possible to produce holes which were substantially freefrom taper and had smooth walls comparable to or even better than thoseproduced by conventional punching followed by a secondary shavingoperation which removes a few thousandths of an inch of metal from thewall of the pierced hole.

Substantially narrower clearances could be used between the highvelocity punch and its die than are required on conventional pressespiercing corresponding holes in corresponding material. For example,conventional die clearances on the link plate material used are of theorder of 6% of the stock thickness, or about .005" each side, for .080"stock. We operated the high velocity machine satisfactorily withclearances of the order of .001" on each side or .002 on the diameter.Both clearance width and ram velocity affects hole shape and size. Inlink plates punched experimentally on the above machine, an increase inpunch velocity from 358 to 690 feet per minute increased hole diameterfrom .2740 to .2745 inch with the same tools. A punch and die clearanceof .0055 on the diameter produced holes which were larger on the punchexit side, .0024" clearance on the diameter produced straight holes, and.0014" clearance on the diameter produced holes larger on the punchentrance sidethat is with the taper reversed from that which occurs withconventional punching.

The link plates being punched were of the type used in powertransmission chain, in which the load is transmitted from link to linkby the bearing contact between the hole walls of the link plates and thepins received in such holes. It will be understood that the smoothnessand straightness of the hole walls have a critical influence on the areaand character of the bearing surface available to transmit the load.

In addition to providing smoother and more nearly cylindrical holes, apunch press employing our invention has other substantial advantages.For example, a press having the specifications set forth above iscapable of performing punching operations which would require a 13- tonpunch press of conventional type. The machine is therefore much lighterin weight and occupies considerably less floor space. Further, since thedownward effort applied to the ram is directed parallel to the path overwhich the ram reciprocates, the ram-guiding means is not subjected tothe side loads and wear which result from inclination of the connectingrod or link in presses of the conventional type.

The shearing machine shown in FIGS. 7-11 is one adapted to cut pins ofpredetermined length from intermittently fed stock in the form of a rodor wire. The stock-feeding means, which is of known type, comprises astationary stock-clamp 91 and a second clamp 92 which reciprocates overa path parallel to the stock 90. During the forward or feeding stroke ofthe clamp 92 such clamp is closed to grip the stock, while the clamp 91is released, with the result that the stock is fed forwardly into ashear 93. During the reverse stroke of the clamp 92, it is re leasedwhile the clamp 91 is closed to hold the stock in fixed position as theshear operates to sever a pin. The

.piston is mounted in stationary position.

stroke of the reciprocating clamp 92 .is of controlled lengthcorresponding to the length of the pins to be cut from the stock. Theclamps 91 and 92 and the shear 93 may all be supported from a base 94and operated by a common, continuously rotating drive shaft 95 extendingalong the rear of the base.

The particular shear shown in the drawing comprises a stationaryshear-member 96 and a horizontally reciprocating shear member 97,respectively carrying abutting bushings 98 and 99 of hard material whichreceive the stock and perform the shearing operation. Both of the shearmembers are mounted in a block 100 supported in fixed position from thebase 94. As shown, the movable shear member 97 is received between upperand lower wear shoes 101 (FIG. 8) in the block 100 and is acted on by athird shoe 102 urged by springs 103 in a direction to maintain theadjacent ends of the bushings 98 and 99 in abutting relationship, asindicated in FIG. 10. A compression spring 104 acts on the movable block97 to urge it toward a position, determined by engagement of a flange105 on the block with the shoes 101, in which the openings in thebushings 98 and 99 are in alignment with each other to permit the stock90 to enter the bushing 99 during the feeding stroke of the clamp 92.

After completion of the feeding stroke of the clamp 92 and closing ofthe clamp 91, forward movement of the shear member 97 will cause a pinto be sheared from the stock 90, the sheared pin remaining in the member97 until forced therefrom by the stock 90 in its next advance. Shearedpins pass through a hole 107 in the shoe 102 and fall into a drop chute108 (FIG. 7).

As in the machine shown in FIGS. 1-6, the movable cutting element, inthis case the movable block 97, is

forced through its operating stroke as a result of being struck by a ramdriven by a body of gas maintained under elevated pressure. The machineof FIGS. 7-11, however, diifers from that of FIGS. 1-6 in that thecylinder, which, in part contains the body of pressurized gas, is formedin the reciprocating ram, while the associated Other differences betweenthe two machines reside in the means employed to retract and release theram and in the use of the spring 104 to retract the movable cuttingelement.

In the arrangement shown in FIGS. 7-11, the shear 93 is mounted on aplate 110 provided, in rear of the shear, with spaced, upwardlyextending front and rear posts 111 and 112. The front post slidablyreceives the ram 113, which is provided at its front end with acentrally located boss 114 adapted to engage the movable shear member97. At its rear end, the ram 113 is provided with a centrally locatedcylindrical recess 116 constituting a cylinder which receives a piston117 mounted in fixed position on and projecting forwardly from the rearpost 112. An axial passage 118 extending through the piston 117 connectsthe cylinder 116 with a passage 119 extending upwardly through the rearpost 112 and communicating at its upper end with an accumulator 120. Asupply of gas under pressure is maintained in the accumulator 120 andcylinder 116, as by the means employed for the purpose in the machine ofFIGS. l-6. The passages 118 and 119 should have as large across-sectional area as practicable in order to avoid throttling of gasdisplaced between the cylinder 116 and the accumualtor 120.

For the purpose of retracting the ram 113 against the force exerted onit by the pressurized gas in the cylinder 116, we employ a reciprocableyoke 121 comprising a front member 122 and a rear member 123 rigidlyinterconnected by shouldered bolts 124 slidably received in the rearpost 112. The ram 113 is loosely received in the front yoke member 122,whose rearward movement relative to the ram is limited by its engagementwith an abutment in the form of an annular flange 126 provided at therear end of the ram. There is thus provided be- 'tween the yoke and theram a lost-motion connection by means of which the ram may be retractedin rearward movement of the yoke and temporarily retained in retractedposition while the yoke moves forwardly.

The yoke is reciprocated in timed relation with the stock-feedingmechanism by means of an eccentric 127 carried by the drive shaft 95,such eccentric being received in the rear end of a connecting rod 128Whose front end is pivotally connected to the rear yoke-plate 123, as bya pin 129. To retain the ram in retracted position until the moment itis to be released to drive the movable shear member 97 through itscutting stroke, we provide a latch 131 pivotally mounted in the rearpost 112 and adapted to engage the ram-flange 126 and retain the ram inretracted position until the latch is released. A spring 132 resilientlyurges the latch toward engagement. For the purpose of releasing thelatch, it is provided with an upwardly projecting tail 133 located inthe path of movement of a pin 134 projecting forwardly from the rearyoke-plate 123.

In FIG. 11, the parts of the shearing mechanism are shown in thepositions they occupy at the completion of a shearing operation. Theyoke 121 is at the forward limit of its movement, as is also the ram113, which has struck the movable shear member 97 and driven itforwardly to shear the stock and compress the spring 104. It will benoted from FIG. 11 that in the position of the parts there shown thefront yoke plate 122 is spaced forwardly from the ram-fiange 126 toprevent it from interfering with the forward movement of the ram 113under the influence of pressure in the cylinder 116. In the rotation ofthe drive shaft, the yoke 121 is moved rearwardly, bringing the frontyoke plate into engagement With the ram flange 126, retracting the ram,and permit ting the spring 104 to restore the movable shear-member 97 toits normal position (FIG. 10) in which the bushings 98 and 99 arealigned. As the ram nears or reaches the limit of its retractingmovement, the ram-flange 126 clears the latch 131, which is then movedupwardly by the spring 132 into engaging position in front of the ramflange. As a result, when the yoke moves forwardly during continuingrotation of the drive shaft 95, the ram does not follow it but isretained in retracted position by the latch. As the yoke nears theforward end of its movement, the pin 134 on it strikes the latch-tail133 and releases the latch, thereby permitting the ram to move forwardlyunder the accelerating influence of the pressurized gas in the cylinder116, strike the movable shear-member 97 and drive it through its cuttingstroke. Forward movement of the ram is limited by a pad 136 of rubber orlike resilient material secured to the rear face of the block 100, whilea similar pad 137 mounted in the block 100 limits forward movement ofthe shear-member 97.

Since the shearing mechanism and the stock-feeding mechanism are bothdriven by the common drive shaft 95, they will operate in timed relationto each other. Feeding movement of the stock occurs after retraction ofthe ram has begun and the spring 104 has brought the cutting bushings 98and 99 into alignment.

As in the case of the link-plate punching machine of FIGS. 16, the pinshearing machine of FIGS. 7-11 is a true shearing machine in which thestock is stressed in shear to the point of fracture by dies which movein a direction to pass each other with a close clearance. The pinshearing machine, like the punching machine, produces materially betterresults than are obtainable on conventional shearing presses.Conventional machines tend to produce pin ends which are deformed byplastic deformation and which have an objectionable rounded corner orradius where the shearing cut began that merges into a crescent-shapedcut band where the tool has penetrated the cross-section before fractureoccurred, and on which the major portion of the end face is an obliquefracture surface. While conventional shearing has been used on smallsized pins of hard material; if otherwiseacceptable lower-cost materialis used, conventionally sheared pin ends are neither fiat nor square,and require secondary finishing operations, as in a coining press, ifthe pins produced are to be used in an assembly such as powertransmission chain Where pin end shape and finish is of importance. Ournew high velocity shearing produces pin ends which have little or nocorner radius, have a narrower cut band than conventional sheared pins,and have a substantially flat and smooth fracture surface which issubstantially square With the pin surface. The ends are of such goodquality and trueness that secondary operations may be eliminated withoutlowering quality standards. Moreover, the high velocity shearing willproduce pin blanks which meet high quality standards without requiringsecondary end-finishing operations, in sizes which it was not possibleto produce to the same standards by conventional shearing, and whichrequired more expensive sawing or screw-machine operations. To out such*la-rger-size pins, we have used substantially higher velocities.

As in the case of the machine of FIGS. 1-6, the proportions of ashearing machine such as that of FIGS. 711 will depend upon the effortrequired to perform the shearing operation. A machine which has beenemployed to shear 0.2 inch carbon-steel rod having a tensile strength inthe neighborhod of 150,000 p.s.i. had the following specifications:

Weight of ram lbs 16 Weight of moving shear parts lbs 1.5 Cylinderdiameter inches 3.5 R-am travel to impact inch Pressure incylinder-accumulator p.s.i 42 Volume of cylinder-accumulator (approx)cu. in 115 Stroke frequency per min 200 In this case, the ram attained avelocity of feet per second before impact.

For shearing larger rod, up to .566" diameter steel rod, we have used aram weighing 8 pounds, a movable die weighing 0.8 pound, and a ramvelocity at impact of approximately 50 feet per second.

For such larger diameter rod, a production machine in accordance withthe invention may utilize the following representative values:

'Pin size in W Shear strength of pins lb./sq. in" 85,000 Ram weight lbs5.3 Movable die weight lbs 2.8 Velocity imparted to die ft./sec 49.2 Ramenergy before impact ft. lbs 198 Energy imparted to die ft. lbs 105Energy required to shear pin "ft. lbs 102 Excess die energy ft. lbs 3Excess ram energy "ft. lbs 18.5

We claim as our invention:

1. In a shearing machine, having a stationary shearing element and amovable shearing element movable relative to the stationary element toperform a cutting operation by stressing in shear to the point offracture a workpiece placed between them, a reciprocable ram movableover a predetermined path into and out of engagement with the movableshearing element, means constantly urging said ram toward engagementwith the movable shearing element, said means comprising a cylinder andpiston one of which is movable with the ram, a rotatable shaft, meansincluding a cam carried by said shaft and operable in rotation thereofto move the ram to a retracted position spaced from said movableshearing element and then to release it to permit fluid-pressure in saidcylinder to force the ram toward engagement with said movable shearingelement, means for maintaining fluid pressure in said cylindersufiicient to accelerate the ram to a velocity such that, upon strikingthe moving shearing element following its release, it will cause themovable shearing element to perform the shearing operation, meansindependent of said cam for limiting movement of the ram after it hasstruck the movable shearing element, and means operated in timedrelation with said shaft for moving said movable shearing element to itsretracted position while the cam is moving the ram to its retractedposition.

2. A machine as set forth in claim 1 with the addition of releasablemeans for holding the rain in retracted position.

3. A machine as set forth in claim 1 further characterized in that thevolume of said cylinder is many times the displacement of said piston.

4. A machine as set forth in claim 1 with the addition of means operatedin timed relation with said shaft for feeding work into position to beoperated on by said shearing elements and means for interruptingoperation of said feeding means while said shaft continues to rotate.

5. A machine as set forth in claim 1 with the addition of means operatedin timed relation with said shaft for feeding work into position to beoperated on by said shearing elements.

6. A machine as set forth in claim 1 with the addition of means operatedin timed relation with said shaft for feeding work into position to beoperated on by said shearing elements and means operable tosimultaneously retain the ram in retracted position and interruptoperation of said feeding means.

7. A machine as set forth in claim 1 with the addition that said ramincludes an impact member engageable with the movable shearing elementand adjustable in the ram in a direction parallel to the path of rammovement.

8. A machine as set forth in claim 1 in which the cam has a progressivecam rise terminating in an abrupt drop off and the ram is retracted bysuch rise and is released by the cam drop off.

9. A machine as set forth in claim 1, in which the cam has a progressivecam rise to retract the cam and acts thereon through a lost motionconnection, with the addition of a latch to retain the ram in retractedposition, and means to unlatch the latch to release the ram when the camhas moved to a position providing lost motion in its connection to theram.

10. A machine as set forth in claim 9 in which the latch is released inresponse to movement of the cam to said lost-motion-providing position.

11. In a shearing machine having a stationary shearing element and amovable shearing element movable in passing relation to the stationaryelement to perform a cutting operation by stressing in shear to thepoint of fracture a work-piece placed between them, a reciprocable rammovable over a predetermined path into and out of engagement with saidmovable shearing element, means constantly urging said ram towardengagement with said movable shearing element, power-operated means formoving the ram against the effort exerted on it by said ram-urging meansto a retracted position spaced from said movable shearing element andthen releasing it to permit said ram-urging means to force the ramtoward engagement with the movable shearing element, said ram urgingmeans exerting on the ram a force sufiicient to impart to the ram beforeit engages the movable shearing element a kinetic energy at least equalto that required both to accelerate the movable shearing element to avelocity of at least 6 to 8 feet per second and to cause the movableshearing element to perform the cutting operation and means forretracting the movable shearing element after the cutting operation.

12. In a shearing machine as set forth in claim 11 in which said meansfor retracting the movable shearing element is power-operated in timedrelation with said ramretracting means.

13. In a shearing machine as set forth in claim 11 in which said meansfor retracting the movable shearing element is a spring means.

14. A shearing machine as set forth in claim 11, with the addition ofmeans independent of the movable shearing element for limiting movementof the ram after it has struck said element.

15. A shearing machine as set forth in claim 14 with the addition ofmeans independent of the work for limiting movement of the movableshearing element after it has performed the cutting operation.

16. A shearing machine as set forth in claim 11 with the addition ofhold-down means for holding the workpiece against the stationaryshearing element during the cutting operation.

17. In a shearing machine as set forth in claim 11 in which the ram isaccelerated to a velocity to impart to the movable shearing element avelocity of at least to 12 feet per second.

18. A shearing machine as set forth in claim 11 with the addition ofreleasable means for retaining the ram in retracted position.

19. A shearing machine as set forth in claim 11 with the addition ofmeans operable in timed relation with said power-operated means forfeeding work into position to be sheared by the shearing elements, andmeans for interrupting operation of said feeding means while saidpower-operated means continues in operation.

20. A shearing machine as set forth in claim 11 with the addition ofmeans operable in timed relation with said power-operated means forfeeding work into position to be sheared by the shearing elements.

21. A shearing machine as set forth in claim 11 with the addition ofmeans for varying the extent to which the movable shearing element ismoved while engaged by the ram, said means including a stationary memberengageable by the ram after it has struck the movable shearing element.

22. A shearing machine as set forth in claim 11 in which said ram-urgingmeans comprises stressed resilient means which maintains a highram-accelerating force on the ram throughout the forward movement of theram.

23. In a shearing machine, having a stationary shearing element and amovable shearing element movable relative to the stationary element toperform a cutting operation by stressing in shear to the point offracture a work-piece placed between them, a reciprocable ram movableover a predetermined path into and out of engagement with the movableshearing element, means constantly urging said ram toward engagementwith the movable cutting element, said means comprising a cylinder andpiston one of which is movable with the ram, means to move the ram to aretracted position spaced from said movable shearing element and then torelease it to permit fluid-pressure in said cylinder to force the ramtoward engagement with said movable cutting member, means to maintainfluid pressure in said cylinder sufficient to accelerate the ram to avelocity to impart to the moving shearing member, upon striking the samefollowing its release, a velocity of at least 6 to 8 feet per second tocause the movable shearing element to perform the cutting operation, andmeans operating in timed relation with said ram-retracting means formoving said movable shearing member to a retracted position while saidmeans is moving the ram to its retracted position.

24. In a shearing machine, having a stationary shearing element and amovable shearing element movable relative to the stationary element toperform a cutting operation by stressing in shear to the point offracture a work-piece placed between them, a reciprocable ram movableover a predetermined path into and out of engagement with the movableshearing element, resilient means constantly urging said ram towardengagement with the movable shearing element, a rotatable shaft, meansincluding a cam carried by said shaft and operable in rotation thereofto move the ram to a retracted position spaced from said movableshearing element and then to release it to permit said resilient meansto force the ram toward engagement with said movable cutting member,said resilient means being stressed to maintain a force on said ramsufficient to impart to it before it engages the movable shearingelement a kinetic energy at least equal to that required both toaccelerate the movable shearing element to a velocity of at least 6 to 8feet per second and to cause the movable shearing element to perform theshearing operation, means independent of said cam for limiting movementof the ram after it has struck the movable shearing member, and meansoperating in timed relation with said shaft for moving said movableshearing member to its retracted position while the cam its moving theram to its retracted position.

25. In a shearing machine, having a stationary shearing element and amovable shearing element movable relative to the stationary element toperform a cutting operation by stressing in shear to the point offracture a work-piece placed between them, a reciprocable ram fordriving the movable shearing element through the shearing operation,resilient means urging said ram in a shear actuating forward direction,power-operated means for moving the ram against the effort exerted on itby said resilient means to a retracted position and then releasing it topermit the resilient means to force the ram forward to drive the movableshearing element through a shearing operation, said resilient meansexerting on the ram a ram-accelerating force suflicient to impart to theram before the shearing operation begins a kinetic energy sufficient tocause the movable shearing element to perform the shearing operation atan initial velocity of at least 6 to 8 feet per second, and means forretracting the movable shearing element to a work-piece clearingposition while the ram is moved to its retracted position.

26. A shearing machine as set forth in claim 25 in which said resilientmeans comprises an expansible gas chamber in which the gas pressure actsto urge the ram forward, and means to maintain said chamber underelevated pressure to exert continuous ram-urging force.

27. The method of producing an improved sheared face on a work-piecewhich is cut by stressing the same in shear to the point of fracturebetween a stationary shearing element and a movable shearing elementconfined to move in passing relation with the stationary shearingelement, which comprises applying to the movable shearing element, inthe direction of movement thereof, an accelerating force adapted toimpart to the movable die element as it starts the shearing operation avelocity of at least 6 to 8 feet per second and more than sufficientkinetic energy to shear the material being acted on by the shearingelements.

28. The method of producing an improved sheared face on a work-piecewhich in cut by stressing the same in shear to the point of fracturebetween a stationary shearing element and a movable shearing elementconfined to move in passing relation with the stationary shearingelement, which comprises driving the movable shearing element throughits shearing movement at an initial velocity of at least 6 to 8 feet persecond.

29. In a shearing machine having a stationary shearing element and amovable shearing element movable from a retracted position past saidstationary element in a forward direction to perform a cutting operationby stressing in shear to the point of fracture a. work-piece placedbetween the shearing elements, a reciprocable ram movable in a forwarddirection from a retracted position to force said movable elementthrough a shearing opera tion, resilient means acting forwardly on saidram with a. force equal to at least several times the combined weightsof said ram and movable shearing element, said retracted position of theram being spaced far enough from the stationary shearing element thatsuch force accelerates the ram to a velocity of at least 6 to 8 feet persecond before the movable shearing element begins its cutting operation,and power-operated means for restoring the ram and movable shearingelement to re- 15 16 tracted position after completion of a shearingopera- References Cited by the Applicant tion.

References Cited by the Examiner UNITED STATES PATENTS 423,119 3/1890Breuer. UNITED STATES PATENTS 5 957 942 5 1910 Eden 655,267 8/1900Obermeyer 83-628 X 1,431,651 10/1922 Goldman. 1,859,372 5/1932 Mutschler 83-423 X 1,983,842 12/1934 Drucker. 2,039,840 5/1936How1and-Sheannan 225-93X 3 09 015 7/19 3 Bradbury 2,602,507 7/1952 Adams83587 2,708,970 5/1955 Taylor 8359O X FOREIGN PATENTS 2,850,093 9/1958DAngelo et a1 83-586 10 428,674 5/1935 Great Britain. 2,956,464 10/1960Ch-arron 83257 FOREIGN PATENTS WILLIAM W. DYER, JR., Primary Examiner.

279,229 10/ 1927 Great Britain. L. B. TAYLOR, Assistant Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent Noo3,273,434 September 20, 1966 Albert F, Hausman et ale It is herebycertified that error appears in the above numbered patent requiringcorrection and that the said Letters Patent should read as correctedbelow.

Column 1, line 58, for "characteristics" read characteristic column 3,line 44, for "pervent" read prevent column 6, line 3, for "its" read itlines 4 and S, for "position" read position, column 9, line 63, for"accumultor" read accumulator column 14, line 13, for "its", firstoccurrence, read is line 52, for "in" read is -Q Signed and sealed this29th day of August 1967o (SEA L) Attest:

ERNEST W. SWIDER EDWARD J. BRENNER Attesting Officer Commissioner ofPatents

1. IN A SHEARING MACHINE, HAVING A STATIONARY SHEARING ELEMENT AND AMOVABLE SHEARING ELEMENT MOVABLE RELATIVE TO THE STATIONARY ELEMENT TOPERFORM A CUTTING OPERATION BY STRESSING IN SHEAR TO THE POINT OFFRACTURE A WORKPIECE PLACED BETWEEN THEM, A RECIPROCABLE RAM MOVABLEOVER A PREDETERMINED PATH INTO SAID AND OUT OF ENGAGEMENT WITH THEMOVABLE SHEARING ELEMENT, MEANS CONSTANTLY URGING SAID RAM TOWARDENGAGEMENT WITH THE ENGAGEMENT SHEARING ELEMENT, SAID MEANS COMPRISING ACYLINDER AND PISTON ONE OF WHICH IS MOVABLE WITH THE RAM, A ROTATABLESHAFT, MEANS INCLUDING A CAM CARRIED BY SAID SHAFT AND OPERABLE INROTATION THERETO TO MOVE THE ARM TO A RETRACTED POSITION SPACED FROMSAID MOVABLE SHEARING ELEMENT AND THEN TO RELEASE IT TO PERMITFLUID-PRESSURE IN SAID CYLINDER TO FORCE THE RAM TOWARD ENGAGEMENT WITHSAID MOVABLE SHEARING ELEMENT, MEANS FOR MAINTAINING FLUID PRESSURE INSAID CYLINDER SUFFICIENT TO ACCELERATE THE RAM TO A VELOCITY SUCH THAT,UPON STRIKING THE MOVING SHEARING ELEMENT FOLLOWING ITS RELEASE, IT WILLCAUSE THE MOVABLE SHEARING ELEMENT TO PERFORM THE SHEARING OPERATION,MEANS INDEPENDENT OF SAID CAM FOR LIMITING MOVEMENT OF THE RAM AFTER ITHAS STRUCK THE MOVABLE SHEARING ELEMENT, AND MEANS OPERATED IN TIMEDRELATION WITH SAID SHAFT FOR MOVING SAID MOVABLE SHEARING ELEMENT TO ITSRETRACTED POSI-
 27. THE METHOD OF PRODUCING AN IMPROVED SHEARED FACE ONTHE WORK-PIECE WHICH IS CUT BY STRESSING THE SAME IN SHEAR TO THE POINTOF FRACTURE BETWEEN A STATIONARY SHEARING ELEMENT AND A MOVABLE SHEARINGELEMENT CONFINED TO MOVE IS PASSING RELATION WITH THE STATIONARYSHEARING ELEMENT, WHICH COMPRISES APPLYING TO THE MOVABLE SHEARINGELEMENT, IN THE DIRECTION TO IMPART TO THE MOVABLE DIECELERATING FORCEADAPTED TO IMPART TO THE MOVABLE DIE ELEMENT AS IT STARTS THE SHEARINGOPERATION A VELOCITY OF AT LEAST 6 TO 8 PER SECOND AND MORE THANSUFFICIENT KINETIC ENERGY TO SHEAR THE MATERIAL BEING ACTED ON BY THESHEARING ELEMENTS.